Ethers from reactive acid liquor



Patented Oct; 8, 1940' rnnns ritonnmo'rrvn Ac n LIQUOR f Francis M. Archibald, Elizabeth, andHehnuth G,j N

Schneider, Roselle, N. J assignorsto Standard Alcohol Company Applioationhfiifilfli1938, Serialhlo. 203,266

V 6 Claims. rotted-" 1h 1 it This invention relates to an improvement in themanufacture of ethers, and more particu- 27,19 3s. A v v Ethers are prepared from alcohols'tor olefins larly to the productionof ethersfrom the reactive acid liquors prepared by the absorption ofolefins in sulfuric acids. i v This application is a continuation-in-part of U. S. applications. N. 83,896-fi1ed June 6, 1936, now U. 8. Patent No. 2, 131,030, issued September bydissolving the'alcohols or olefins in acids and distilling off ethers that are formed. vThe iormation oi ethers'whenprepared "from alcohols and acid or dissolved olefinsand acid (eittractl is an equilibrium reactiOnJflAt any given"acid strength the conversionof i ethers is increased" byraising the olefin or alcohol to aci'd'mol' ratio. Temperatures from 28 to 100 :C. have only'veryf i slightefiect on the equilibrium." r

it The conversion to ethers is favored for any giveniacid strength by havinga large excess of alcohol present as can be seen from the following experimentalfresults: L

gums benufound that the eq libriumat any temperature was more rapidly reached from the ether-acid: and" olefin-acidside thanffromi the alcohol-acid,side.. The concentration of the acid usedhas agreat effect on the reaction. Where sulfuric acid is used, an. acid off 50 to 60% eifective strength is preferred. Whenhigher.con-

centrations of sulfuric acid are used, the formation of polymers is greatly increased and with weaker acids, ether formation is very slow, although it is possible by raising the temperature to increase the ether formationrate, since-the temperature coeifi'cientof'the ether-forming r eaction is high. These observations apply ticthe.

socjalled batch process. Where a continuous process is mployed, the acid concentration in* "the absorbent medium can behigher withoutformationof tpolymersbecause of the shorter time of contact between the olefin and thetacida Acids as low a as 30%- concentration have been used "and gave satisfactory results. While sill- 55 'furic acid is the preferred catalyst; otherma-r terials may be'used as wel1,;for,example, phos phoric acid, hydrochloric acid; etcflwithvtheiri concentrations adjusted to form alkyl esters more readily.

119 11 a e a o b tained when 80 to 95% acid is used .as the. ab-

80 to195% concentratiom a reactive acid liquor is" obtained. reactive acid liquor is diluted usuallyt'o 20 or 50% to hydrolyze and on distillati'on, alcohols with a small amount of ether are obtained, According to this invention, the reactive acid'liquor is not greatly diluted but only partially, i. e., 45 to-65%"" concentration, and uponheating of this'partially diluted re-* activeacid liquor, a greater proportionof 'ethers isobtaine'd than by acids of 60 to 80% are used asthe absorbent medium, the reactive acidliquor formed when diluted to 140' to 65% concentration and heated, produces ethers: in -yield=equivalent .to that obsorbent medium, the: amount of dilutionQbeing always governed by thelconcentrationiof the acid used for absorption and "the concentration of acidreactant liquordesiredw The yield of ether obtained in all cases is governed by the mp1 ratio of olefine to acid in the extract, the higher this ratio, the greater thegconversion to ether as shown in the table at the left! I The invention will be fully"'understood; from the following. description and 'ldrawing." The drawing represents a diagrammatic view insectional elevation of an apparatus adapted to carry out the process of thesinvention and indicates the flow of materials. t H

Either pure olefins or mixtures of ,olefihs with saturated hydrocarbonsareabsorbed ini acids of suitable strength (usually 60jto 89%)jjiii' accord- A ance with! thelprior jart. They reactive acidliquor so obtained is passed throughpipe I. At

the beginning of the operation of this process'35 the reactive acid liquor is dividedinto twoequal parts and one part is passed throughpipe 2, provided with valve .3, into a nst ipping towern l. Water sufficient to dilute the acid liquorlto 40 to 65% is added to hydrolyze the reactive acid 40 liquor passed into the stripping tower! by means of pipe 5, provided with valve 6. The stripping tower 4 is operatedto, recover the alcohol from i the extract by any method known to the art. The alcoholthat hasbeen formed is vaporized and removed through pipe 3. T j I The dilute acid, after removal of the alcohol, ispassed to storage (notshown) through pipe 9;';provided with :valve' 10. The other half of the reaetiveacid liquor; is passed through, pipe ll into a reaction tower l2, where atemperature ofabout 80 to 130 0., preferably 100: (3., and a pressure of 100 to 200 pounds per square inch ismaintained.

Into this tower is also 'passed'thefalcohol -vapors obtained from thek'stripping tower 4. A

1 mixture of reactive acid liquor and recovered alcohol is maintained in this tower for about four v, .t i hours-{the temperature being controlled by dlm su furiczlacidlsofl. zi a means of steam coil I3.

the former method. When is stripped andremoved by means of is removed from the bottom of the fractionating tower through pipe 23, and upon mixing with the reactive acid liquor returned to the reactiondrum 12. When alcohol is being'recovered from the fractionating tower 20, it is not necessary to use the stripper 4 to obtain any alcohol;

All of the reactive acid liquor is passed directly into the reaction tower I2, together with sufficient recovered alcohol from the fractionating tower 20 to dilute the acid to a concentration less than 65% sulfuric acid. When necessary, as a fine adjustment, additional water is admitted by pipe 24, provided with valve 25, to maintain the proper concentration. The amount of alcohol that is used to dilute the reactive acid liquor is always regulated so that a favorable highratio of alcohol to acid is present.

Example 1 830 cc. extract (solution of propylene in 92% H2804) (mol ratio olefin'to acid 1.3/1.0) and 1050 ccisopropyl alcohol were heated overnight at 100 C. The pressure developed was 130 lbs.

Total alcohol in charge 1551 cc.

Recovered:

668 cc. isopropyl ether 782 cc. isopropyl alcohol Conversion of alcohol to ether based on alcohol reacted=92.6% Conversion of alcohol to other based on alcohol charged=46.5%

Example '2 ""r Charged:

1420 cc. isopropyl alcohol;

340 cc. 95% H2SO4 Heatedovernight at 98-100 C. Pressure developed: 125 lbs. per square inch.

Recovered:

477 cc. ether 865cc. alcohol Conversion of alcohol to ether based on alcohol reacted=93.3% Conversion of alcohol to ether based on alcohol charged=36.4%

Example 3 Charge:

3380 cc. isopropyl alcohol 400 cc. 95% H2804 This yielded a 30% effective acid with the mol ratio of alcohol to acid of 11.4; heated to 96 C.

and developed a pressure of 250 pounds per square inch. 1

' Recovered:

Example 4 v 1000 cc.'71% acid extract (1 molar saturation) 700 cc. isopropyl alcohol Heated to 100 C. for 4 hours.

oped 130#/sq. in.

Pressure devel- Total alcohol charged=1220 cc.

The efiective strength of the sulfuric acid is calculated on a basis of total water present as a diluent in the mixture, including both free water and water chemically combined in alcohol.

Alternately, if mixed ethers are to be produced,

another alcohol than that present in the reactive acid liquor is added. It is not necessary to dilute the reactive acid liquor with the same alcohol which is present in the reactive acid liquor. The distillate therefrom obtained is fractionated in order to segregate the desired alcohol which is to be used to dilute the reactive acid..liquor.

The concentration of sulfuric acid best adapted to form ethers is regulated by the temperatures and pressures used. Sulfuric acids at concentrations of 84% may be used as also may concentrations as low as 1%, but the temperatures and pressures must. be varied accordingly. The pressure generally used is that which develops in the reaction. It is not necessary that alcohol alone be used for dilution, though it is preferred to do so. Water or water and alcohol may be used.

The foregoing description is merely illustrative and various changes and alternative arrangements may be made within the scope of the 'appended claims, in which it is our intention to claim all inherent novelty as broadly as the prior art permits.

We claim:

1. A process for manufacturing aliphatic ethers in which one alkyl group contains at least three" carbon atoms which comprises reacting olefins with sulfuric acid of 60 to 80% concentration to form acid liquors, diluting the acid liquors with alcohols, holding the diluted acid liquors at a reacting temperature until substantially all the acid liquor is reacted, separating the products formed from the sulfuric acid and fractionating the products to obtain ethers and alcohols.

2. A process for manufacturing aliphatic ethers in which one alkyl group contains at least three carbon atoms which comprises reacting olefins with sulfuric acid of 60 to 80% concentration to form acid liquors, diluting the acid liquors with alcohols to reduce the eflective strength of the sulfuric acid to between'40 and 65%, holding the diluted acid liquors at a reacting temperature and super-atmospheric pressure until substantially all the acid liquor is reacted, separating the products formed from the sulfuric acid and fractionating the products to obtain ethersand alcohols.

3. Process for manufacturing ethers according to claim 2 in which the separated alcohols are recycled to dilute the acid liquors.

4. A process for manufacturing aliphatic ethers in which one alkyl group contains at least three carbon atoms which comprises reacting olefins with sulfuric acid of 60-80% concentration to form reactive a'cid liquors, diluting the acid liquors with alcohol to to 65% concentration, holding the said diluted reactive acid liquor in a closed system at a temperature above C. under a pressure such as is developed until substantial equilibrium is reached, separating the sulfuric acid from the alcohol and ethers formed and fractionating the alcohols and ethers.

5. A process for manufacturing mixedaliphatic ethers in whichone alkyl group contains at least three carbon atoms which comprises absorbing olefins in acids of -80% concentration to form acid liquors, diluting the acid liquors with alcohols other than those which could be predominantly produced from the said acid liquors, maintaining the diluted acid liquors at elevated temperatures and pressures until ether formation 7 is substantially complete, separating the products from the said acids and fractionating the products to obtain mixed ethers and the alcohols,

6. A process for manufacturing mixed aliphatic ethers in which one alkyl group contains at least three carbon atoms which comprises reacting an olefin with sulfuric acid of 60-80% concentration to form acid liquors, diluting the acid liquors with alcohols other than those which could be produced from the said acid liquors to a concentration between 40 and maintaining the diluted acid liquors at elevated temperatures and super-atmospheric pressures until the ether formation is substantially complete, separating the products from the acids and fractionating the products to obtained mixed ethers and alcohols. FRANCIS M. ARCHIBALD. HELMUTH G. SCHNEIDER. 

